1. Field of the Invention
This invention relates to a self-contained apparatus for cleaning the vertical surface of a building exterior, including washing the windows, and more particularly to an apparatus which is positioned by an operator above a vertical row of windows and then remotely operated to clean the exterior building surface as the apparatus descends.
Description of the Prior Art
High-rise buildings having fixed glazing have become prevalent in recent years and continue to enjoy great popularity. These buildings have created the necessity of finding a way of cleaning the exterior surface, and architects have responded to the problem in many cases by providing some means of support of scaffolding in the building mullions. In many cases rails have been provided in the mullions so that automated washing machines may be used to clean the exterior building surface. A number of such automatic cleaning devices have been proposed, as for example U.S. Pat. No. 3,604,049 to Hetman; U.S. Pat. No. 3,942,213 to Hohner, Jr.; U.S. Pat. No. 4,025,984 to Hohner, Jr.; U.S. Pat. No. 4,136,419 to Hetman et al; and U.S. Pat. No. 4,198,724 to Fisher et al. It is generally conceded that such machines have not experienced wide acceptance and that a number of problems exist in their application.
U.S. Pat. No. 3,942,213, to Hohner, Jr., for example, describes a wall washing device which uses an air curtain to contain the liquid sprayed against the building exterior. A fan is provided to induce the flow of mist away from the cleaning area and then use the demisted air as an air curtain. The described apparatus, however, employs only a single section for all cleaning functions, and thus is likely to leave a dirty or streaked surface. Nor are means provided for sequencing individual functions, i.e., fluid spray, brushing, wiping, for inset windows, thereby leaving areas at the top and bottom of windows only partially cleaned. In addition, there are no means provided for regulating the pressure in the cleaning chamber and it is thus possible that dirty mist may circulate therein and not be effectively removed.
An additional problem encountered by previous automated washing devices is that of loosening the dirt from the building surface. The prior art means of agitating the dirt loose include direct brush scrubbing, spraying of a liquid, and blowing an air curtain against the surface. Use of air and liquid sprays have been considered to be more desirable than brushing since no direct contact is necessary. However, in the devices, the only way to enhance the loosening power of the spray is to increase the spray pressure, which is inefficient.